1. Field of the Invention
The present invention relates to fertilizers based on peat.
2. Description of the Related Art
Components based on peat are known. The known practice for preparing a peat is to add, to a peat, two or more separate sources of a plant growth or nutrition factor such as, for example, nitrogen, phosphorous and potassium. U.S. Pat. No. 3,307,934 for example indicates that it is known to prepare a peat based granular or aggregate fertilizer by combining peat with added sources of nitrogen, phosphorous and potassium (i.e. N, P and K); see example 1 and 4 of this patent where it is respectively indicated that peat may be associated with urea and diammonium phosphate or urea and ammonia.
It would be advantageous to be able to have an effective peat composition comprising a single added source of nitrogen or a single added source of nitrogen and phosphorous, e.g. to reduce the cost of the starting materials needed to produce an effective peat fertilizer composition and to reduce the labour costs as well (i.e. less manipulation of the starting materials. It would be advantageous to have a means for obtaining a peat fertilizer composition based on a single added source of a plant growth factor. It would in particular be advantageous to have such a fertilizer composition for use in the growth of potatoes, corn, wheat or other crop.
Accordingly, the present invention provides a composition of matter comprising a peat material and an added source of nitrogen, said added source of nitrogen consisting of one of urea, diammonium phosphate, monoammonium phosphate and ammonia. The peat material may be an acidic, humic peat material. The peat material may advantageously be an acid peat of medium to high decomposition, i.e. of relatively high humic acid content.
It is to be understood herein that the expression--added source of nitrogen--refers to a source of nitrogen that is added to or admixed with the peat for the formation of the composition of matter. The added source of nitrogen is either urea, or diammonium phosphate or one of the other above mentioned nitrogen sources.
The added source of nitrogen may be added in any suitable or known manner or form. The added nitrogen source may be added for example as a solid (e.g. particles; as a paste (e.g. with water); as a solution (e.g. an aqueous solution of ammonia and water); if the case permits, as a gas (e.g. ammonia); etc.
The composition may have a nitrogen content, for example, of from 6% to 37% by weight. The peat content of the composition of matter may vary from 20% to 80% by weight.
This composition of matter may take on any desired or necessary form including, for example, a mixture to be used as a pre-cursor or intermediate substance for the preparation of a peat fertilizer in the form of a granule or the like; it includes granules.
In a further aspect the present invention provides in a process for making a peat fertilizer composition comprising a mixing stage wherein a peat material and an added source of nitrogen are mixed so as to form a mixture thereof, the improvement wherein said added source of nitrogen consists of one of urea, diammonium phosphate, monoammonium phosphate and ammonia. As mentioned above, the peat material may advantageously be an acid peat of medium to high decomposition, i.e. of relatively high humic acid content. The mixture may take the form of a pre-cursor or intermediate mixture which may be sent on to an extrusion stage wherein the mixture of peat and the added source of nitrogen are extruded so as to form an extrudate thereof. The extrudate may then be dried and as desired or necessary the dried product may be subjected to a size reduction stage to obtain granules of a desired size or size range.
The peat prior to being intermingled with the added nitrogen source may initially have a water content of from about 25 to 60 percent (e.g. 55 to 60 percent, e.g. 30 percent by weight, e.g. 40 percent by weight).
Once the peat is associated with the so added source of nitrogen, the initial source of nitrogen may subsequently be subjected to an in situ conversion process whereby, if the added source of nitrogen acts effectively as a NH.sub.3 carrier, NH.sub.3 may be formed in situ, e.g. slowly, due to hydrolysis of a non-ammonia nitrogen source (i.e. urea) or volatization (i.e. diammonium phosphate), there may be a conversion thereof to ammonia.
Ammonia interacts advantageously with peat humic acids which is present in the decomposed peat material to produce ammonium humates. The ammonium humates are water soluble. The slow conversion of an ammonia carrier (e.g. urea) to ammonia coupled with the formation of ammonium humates provides an advantageous mechanism for the slow release of nitrogen; the slow release of nitrogen is of utmost importance for environmental protection and efficient use of the nitrogen as fertilizer.
Accordingly, it is advantageous to use a peat material having a relatively high humic acid content, e.g. a peat material which is relatively highly decomposed. The peat material may, for example, have a pH of less than 6.0 e.g. a pH of from 1.5 to 6.0, in particular a pH of from 2.0 to 6.0 (e.g. a pH of 3.0 to 5.0 a pH of 2.0 to 2.5, a pH of 2.0 to 5.0, a pH of 3.0 to 6.0, a pH of 2.0 to less than 3.0, etc.) after equilibration in a solution of KCl 1N (see Karam, A 1993. Chemical properties of organic soils. Pg 459-471, Chapter 44 in: Martin R Carter (ed.) Soil Sampling and methods of analysis, Canadian Soil science Society methods manual. Lewis Publishers Inc., Ann Arbor Mich.). The peat material may have a humification value of H4 or more (e.g. H5 to H7, H9, etc.) on the Von Post humification scale (see Parent, L. E. and J. Caron 1993. Physical properties of organic solids. Pg 441-458, Chapter 43 in Martin R Cater (ed.) Soil Sampling and methods of analysis, Canadian Soil science Society methods manual. Lewis Publishers Inc., Ann Arbor Mich.). The humic acid content of a suitable peat material may, for example, vary from 24 to 37 percent by weight (e.g. 24 to 28 percent by weight). The peat material may in particular be a medium to well decomposed sphagnum or woody-herbaceous peat. Suitable peat material may for example be found in Quebec, Canada, in New Brunswick, Canada, in Michigan, U.S.A., and in Minnesota, U.S.A. Suitable peat material may, for example, be obtained from Fafard Peat Moss Ltd., Pallot Road, Inkerman, New Brunswick, Canada; a peat material of about pH 2.28 may for example be obtained from Fafard Peat Moss Ltd.